Physiology of jack semen

In 1937 a project to study the problem of jack stock and mule production was initiated at the Tennessee Experiment Station. As the work progressed, it became apparent that the possibilities of using artificial insemination in mule production needed to be studied. It was envisioned that with the decline in jack stock, it might become necessary for a small number of jacks to furnish services for a large number of mares to maintain the necessary mule population for farm work. To accomplish this, artificial breeding seemed to be the only alternative.

Most of the studies pertaining to the application of artificial insemination have been restricted to the dairy industry. Dairy bull semen can be transported long distances and used successfully after days of storage. Such is not the case with jack sperm. In undiluted semen, the sperm lose their motility within a few hours and even in diluted semen they do not retain their fertilizing capacity nearly as long as do bull sperm.

The sperm is a most sensitive and delicate organism and must be placed in some media to preserve its viability. One of the many problems in artificial insemination is finding a satisfactory diluent for the semen of a particular specie. This study was initiated in an attempt to find a diluent for jack semen in which the sperm could be stored for a longer period and at the same time maintain their fertilizing potentiality.